As a semiconductor device has been getting miniaturized, a line width is required to be about 20 nm or less. In order to get such a line width, development of an extreme ultraviolet light (hereinafter, referred to as “EUV light”) exposure apparatus using an EUV light as an exposure light or an electron beam exposure apparatus using an electron beam as an exposure light has been progressing. In the EUV exposure apparatus, since the EUV light cannot penetrate the atmosphere, a photoresist film is exposed under vacuum. Further, in the electron beam exposure apparatus, since the electron beam is emitted from an electron gun, a photoresist film is exposed under vacuum. Meanwhile, since coating or developing photoresist on a wafer is carried out under an atmospheric pressure, a load-lock chamber serving as an interface unit is indispensable between the photoresist coating and developing apparatus and the exposure apparatus (see, for example, Patent Document 1).    Patent Document 1: Japanese Patent Laid-open Publication No. 2008-34739
However, when photoresist patterns each having a line width of about 20 nm or less are formed through an exposure process, alignment of patterns may be deviated due to thermal expansion of a wafer. Accordingly, temperature of the wafer under an exposure process needs to be maintained at a constant temperature. For this reason, the EUV exposure apparatus or the EB exposure apparatus is provided with a temperature control device and, thus, a temperature of the wafer can be controlled to be, for example, 23±0.02° C.
Further, in order to improve throughput, a temperature of a wafer needs to be quickly adjusted. Thus, the temperature of the wafer needs to be controlled in a photoresist coating and developing apparatus before the wafer is loaded into an exposure apparatus.
Considering these circumstances, the inventors of the present invention examined a control of the temperature of the wafer in the photoresist coating and developing apparatus. As a result of the examination, it has been found that even if the temperature of the wafer is precisely controlled in the photoresist coating and developing apparatus, the temperature of the wafer is greatly decreased due to adiabatic cooling occurring when depressurization is carried out in the load-lock chamber, and, thus, it is useless to control the temperature in the photoresist coating and developing apparatus.
Hereinafter, there will be explained how much a temperature of the wafer is decreased with reference to a result of an experiment conducted by the present inventors in a process of completion of the present disclosure. FIG. 1 shows a change in temperature of a wafer in a load-lock chamber. To be specific, in this experiment, a thermostat plate was provided in a load-lock chamber and a temperature of the thermostat plate was preset to be about 30° C. Then, a wafer equipped with a temperature measurement sensor (hereinafter, referred to as “test wafer”) of which a temperature had been preset to be about 23° C. was provided in the load-lock chamber. With depressurization in the load-lock chamber, a change in the temperature of the test wafer with time was recorded. In this experiment, the test wafer was mounted on the hot plate at the time indicated by an arrow A1 of FIG. 1, the temperature of the test wafer was increased to about 28° C. Then, depressurization was carried out at the time indicated by an arrow A2 of FIG. 1.
It can be seen from FIG. 1 that if depressurization is carried out in the load-lock chamber, the temperature of the test wafer is sharply decreased. To be specific, the temperature of the test wafer was decreased by about 15° C. in about 40 seconds. Thereafter, the present inventors tried to control the temperature of the test wafer to be about 23° C. by using the hot plate but the temperature did not return to about 23° C. even at the time indicated by an arrow A3, i.e., about 4 minutes after the depressurization start time (the time indicated by the arrow A2).
Further, it can be seen that the temperature of the test wafer is varied in the range of ± about 0.4° C. in the surface at the loading time (indicated by the arrow A1) but it is greatly varied in the range of ± about 1° C. at the time of the lowest temperature (for reference, a plurality of curves in FIG. 1 shows a change in temperature at each measurement point in the test wafer but specific descriptions of the measurement points are omitted). It takes a long time to precisely control a temperature of the wafer after loading the wafer of which a temperature is non-uniformly changed into the exposure apparatus, which causes a decrease in the throughput.
In view of the foregoing problem, the present disclosure provides a photoresist coating and developing apparatus, a photoresist coating and developing method and an interface apparatus capable of reducing a change in temperature of a wafer when the wafer is transferred from the photoresist coating and developing apparatus to an exposure apparatus via a load-lock chamber.